JPH05508987A - Power control for direct sequence CDMA radios - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Power Control for Direct Sequence CDMA Radio Devices Field of Invention TECHNICAL FIELD The present invention relates generally to the field of communications, and more particularly to code division multiple access (CO). de-division muHiple access: CDMA) transmitter electric Regarding force control.

Background of the invention In the direct sequence CDMA (DS-CDMA) wireless telephone system, the end Controls the output power level of the user's radiotelephone transmitter to improve system performance at the base station receiver. Requires some kind of power management scheme to control system interference. DS-CDM For A, John G. Proakis, DigitalCpmmu nications, 2nd Edition, pages 800-84 It is explained in detail in 5. Base station receiver, base station transmitter and user station This power management is performed by a combination of line telephone equipment (mobile stations). The sending radiotelephone has more system capacity than is required for proper communication from the base station to the base station. Prevent the device from being used.

This power control consists of two power control loops: an open loop for initial estimation; This is done by a closed power control loop for correcting this initial estimate. open loop The radiotelephone device that performs step control has a received signal strength indicator (received signal strength indicator). Signal strength 1ndicator: RS SI) is used to estimate the power loss in the signal path from the base station to the wireless telephone device. So Here, the wireless telephone device can compensate for power loss when replying to the base station. . Because the transmit and receive frequencies are generally different and widely separated, The power loss from the ground station to the radio telephone equipment is the same as the power loss from the radio telephone equipment to the base station. are not the same, so this initial estimate must be corrected.

This correction, which modifies the initial estimate, involves power control bits at a rate of 800-1000 times/sec. This is done by the base station which sends the calls to the mobile radiotelephone device. Power bit 1 is , instructs the radiotelephone to increase the power by one power step, and 0 instructs the radiotelephone to reduce power by one power step, but The reverse is also true based on the intended system protocol. 1! Kastep and is generally a set value in the range of 0.5 to 1.5 dB. Closed loop control is generally It has a control range of ±24dB. The total power control range is for mobile stations with a maximum power of 1 watt. It is generally 80 dB.

The power amplifier of a DS-CDMA radiotelephone shall be at least a class AB linear amplifier. Must be. This means that the modulation of the system is partially amplitude-dependent for all modulation schemes. The modulation bandwidth can be modulated by the filter before the power amplifier. is set to control transmitter splatter. be. As is well known to those skilled in the art, the output of a linear power amplifier is Must be controlled by in-1ine attenuationOn It is not controlled by controlling the power supply voltage. For this reason, it is necessary Systems such as DS-CDMA wireless telephone systems, which have a wide range of power control. A problem arises in the system. This wide power control range allows the desired conducted radiation (c spurious from the circuit at a higher level than the inducted radiation. radiation, which can interfere with the desired level of the transmitted signal. Also, this kind of Radiation must be properly shielded to prevent it from interfering with other circuits within the radiotelephone equipment. It is difficult to Furthermore, around the variable attenuation circuit that controls the RF output level There is a problem of conducted leakage. the Therefore, a circuit that performs a variable attenuation function without spurious emissions or leakage problems is possible. Needed.

Summary of the invention The power control device of the present invention includes a local oscillator signal coupled to a mixer via a variable attenuator. path and the IF signal coupled to the mixer via two series-coupled variable attenuators. It consists of a route. These attenuators are controlled by digital control circuits be done. The mixer mixes the attenuated IF scratch signal with the attenuated local oscillator signal. By doing so, a transmission frequency signal is generated.

Brief description of the drawing FIG. 1 shows an electronic device of the invention comprising a receiver front end and a transmitter back end. The force control device is shown.

FIG. 2 shows a general transmit power control circuit according to the present invention.

FIG. 3 shows a schematic diagram of the level shift block.

FIG. 4 shows the transfer function of the level shift block.

Detailed description of the preferred embodiment The wireless telephone power control device of the present invention eliminates the problem of spurious and conducted radiation when transmitting. DS-CDMA signal attenuation. This generates a transmit frequency signal Attenuation is applied to both inputs of the mixer and the power level of this signal is This is done by keeping it below the level of

A power control device of the present invention is shown in FIG. The power control section in FIG. 1 includes elements 106 to 1. Contains 13. Antenna 101 is used to transmit and receive DS-CDMA signals. The typical transmit power control range is from +35 to -51 dBm. Bandwidth communication The filter filters 102 and 103 have duplex filters for transmitter output and receiver input. ) are connected to each other.

Power amplifier 104 provides the required maximum power and gain of the signal from the power controller. at least a class AB linear power amplifier that can It is filtered by filter 105 to the final transmission frequency range.

This power control device consists of a dual path to mixer 106, with one path leading to the local generator. One path is for the vibration signal, and the other path is the modulation section of a general 5-CDMA transmitter. This is the route of the IF multiplied signal. Both paths of the power control device are connected to the transmit power control circuit 111, and this transmission power control circuit 111 has a variable attenuator controlled by It has a digital/analog (D/A) converter and a low pass filter. variable attenuator 108 and 109 are connected in series with the IF flaw signal mixer]06. this These attenuators are controlled by an attenuator control signal 112 from a transmission power control circuit 111. be controlled. The variable attenuator 107 is in series with the local oscillation signal and the second input to the mixer. be. In the preferred embodiment, this attenuator is derived from attenuator control signal 112. This attenuator control signal 112 is controlled by the level shift circuit 110. level shifted and delayed by A preferred embodiment of the power control device is , D I MM I C (dielectrically isolated m onolithic microwave integral cdcircu mouth ), or high-speed bipolar or BI CMOS (bipolar-com plementary metal oxide semiconductor) It can be configured as an integrated circuit. All these integrated circuits are extremely small, so contributes little to spurious emissions that interfere with the desired power control range.

It is necessary to control signal leakage from the IC's IF lead to the IC's local oscillator lead. be. If the full range of power control is done without variable attenuator 107, two signals The isolation between the input leads must be greater than the desired power control range.

This problem reduces the dynamic range of attenuation required in the IF branch. , is overcome by a variable attenuator that reduces the required lead insulation. Desired mixer output Reduces the level of local oscillator signals in the middle or lower end of the force dynamic range There is no problem in doing so. This makes the mixer desensitized. ng)L, has the effect of reducing its gain. At high desired output signal levels, To prevent changes in attenuator control signal 112 from affecting variable attenuator 107, A bell shift circuit 110 is configured. The variable attenuator 107 is a level shift circuit. signal 113 generated by line 110.

In a preferred embodiment of the invention, the local oscillator signal is in the range of 939-964 MHz. It operates with an IF flaw signal of 115MHz. Mixer 106 is +11 to -75 dB The transmitter generates a transmit frequency signal in the range of 824-849 MHz with a power range of m.

This signal is filtered by a bandpass filter 105 before the power amplifier 104. It will be done. Power amplifier 104 increases the power level from +38 to -48 dBm.

This signal is then filtered by a bandpass filter (1o2) and then +35 It is transmitted from the antenna in a power level range of ~-51 dBm. The transmission frequency is first , these common to be produced at levels below the desired antenna output level. From the power level. This applies to the IF branch and local oscillation branch of mixer 106. This is achieved by providing the necessary variable attenuation using a combination of variable attenuators in the be revealed. This allows spurious emissions at the transmit frequency to be transferred to the desired controlled conduction It is guaranteed that the antenna output will be less than or equal to the antenna output.

The attenuator control signal 112 of the power control device of the present invention has a transmit power as shown in FIG. This is done by a control circuit. Input control signal from which attenuator control signal 112 is derived R55I (212), R55I Reference (207) and Tx gain (208). The analog signal R55I (212) is A received signal strength indicator generated by the wideband IF of a DS-CDMA receiver. It is ta. The R55I standard (207) has improved performance compared to R55I (212). It is used as the output of operational amplifier 204 to generate the RXAGC signal. Tx Gain (208) is the cumulative sum of closed loop power control bits received from communication base stations. It is. R8S standard (207) and Tx gain (208) are both digital signals. and in the preferred embodiment, these signals are radio frequency pulse varying rI4 (PWM) It's a signal. These signals are processed in a demodulator ASIC 205 as shown in FIG. can be generated by a microprocessor or DSP as a multi-bit signal. It can then be generated from a D/A converter. The PWM signal is a low-pass filter. It can be easily converted to an analog signal using a filter. R55I group @(2 07) The low-pass filter of the signal consists of a resistor 217 and a capacitor 218 . A low pass filter for the Tx gain signal is provided by resistor 220 and capacitor 221. Become. In the preferred embodiment, the 3 dB corner of these low pass filters er) is 5000Hz.

The RxAGC (223) signal, which is an open loop power control signal, and the closed loop power control signal The low-pass filtered Tx gain (203) signal, which is the signal of the inverting operational amplifier 20 8, this amplifier 203 has at its positive lead the DC supply voltage has an AC ground reference voltage of half that of . Relative open-loop and closed-loop signals The respective contributions are controlled by resistors 216 and 219, respectively. These resistances selected for the return resistor 215, G+”R (216) and G2 R (219) It is written as a tail. These resistances apply to specific DSS-CDMA systems. By appropriately choosing the resistor, an open-loop control signal can be generated at the output of operational amplifier 203. A suitable balance is obtained between the signal and the closed-loop control signal. of operational amplifier 203 The output is provided to the inverting input of another operational amplifier 202 via a resistor 214. resistance The resistor 213 performs the final gain adjustment of the transmit power control signal, and in most cases, Gives a gain rate of 1. Here, the output of the operational amplifier 202 is RxAGC (223) The same sense signal and low-pass filtered Tx gain (208) signal e). This is because amplifiers 202 and 203 perform double inversion.

Attenuators 107, 108, 109 of the power control device transmit power control signals of opposite sense. , the inverting operational amplifier 202 and associated resistors (213, 214 ) can be omitted.

In a preferred embodiment, the output of the operational amplifier (202) is a power amplification control circuit. The signal is passed through a sample and hold circuit (201). In a preferred embodiment, the sample The hold circuit (201) has three A digital control signal is provided. WSymb.

l　C1ock　(209) is a 4800Hz pulsed signal, and is an operational amplification signal. The output of the circuit 202 can be transferred to the output of the sample and hold circuit 201. do. PA0n (210) is the global power amplifier on/off control signal . When PA0n (210) is in the off state, the attenuator control signal 112 (typically about 20 below the lower end of the normal dynamic power control range) dB higher). Tx Punct (211) is a DS-CDMA system. transmitter output when the system is operating below its normal full data rate. This is a signal that can be used for gating. Gating pulse ゛( The period of gating pulse) may be about 1 millisecond, and the repetition rate of several hundred H2 is sufficient. can have a Variable data rate in DS-CDMA systems Another way to achieve Tx power control is to reduce Tx There are ways to reduce power levels. However, this power reduction is Adds to the Namic power control range. Using the TxPunc t (211) signal, By gating the transmitter at its normal full data rate, the power control system The same result is obtained without increasing the dynamic range of the system.

A circuit that can be used for level shifting function 110 is shown in FIG. child The circuit consists of an operational amplifier and a resistor. In the preferred embodiment, these resistors are have the same resistance value. FIG. 4 shows the transfer function of the level shift circuit. Output signal No. 113 is the input signal 112 minus V 611 s e t. This figure shows that. This shift causes the local oscillation signal attenuator 107 to Attenuation is delayed relative to attenuation by signal attenuators 108 and 109.

A power control device for a DS-CDMA radiotelephone device has been described above. child The device controls transmit power over a wide dynamic range and eliminates spurious and Prevent the occurrence of uncontrolled transmit power.

+35~-51.8□ Figure 1 Figure 3 Figure 4 level shift transfer function VoFFstv VIN Man power 112 abstract a local oscillator signal path coupled to mixer 106 via variable attenuator 107; coupled to mixer 106 via two coupled variable attenuators 108, 109. A power control device comprising an IF signal path is provided. IF signal f path attenuator 108 , 109 are controlled by a digital control circuit, and the attenuator 10 in the local oscillation signal path 7 is controlled by a control circuit via a level shifter 110. these two The power level of the signal produced by mixing the signals of the radiotelephone device is Less than the conducted output of the power amplifier.

Claims (10)

[Claims] 1. Code division multiple access communication device having a local oscillator signal and an intermediate frequency (IF) signal An apparatus for controlling transmission power of: means for generating an attenuation control signal; a first controllable coupled to the local oscillation signal to generate an attenuated local oscillation signal; a first controllable attenuator for changing the attenuation in response to the attenuation control signal; damping means; a second controllable attenuator coupled to the 1F signal to produce an attenuated IF signal; a second controllable attenuation for varying the attenuation in response to the attenuation control signal; means; and coupled to said first controllable damping means and said second controllable damping means; generating a transmission frequency signal from the attenuated local oscillation signal and the attenuated IF signal; A device characterized in that it is constituted by: mixing means; 2. a third control coupled in series with said second controllable damping means and said mixing means; possible attenuation means, the third control varying the attenuation in response to the attenuation control signal; The apparatus according to claim 1, further comprising controllable damping means. Place. 3. filtering means coupled to said mixing means for producing a filtered transmit frequency signal; 2. The apparatus of claim 1, further comprising: 4. further comprising power amplification means for amplifying the filtered transmission frequency signal. 4. The device according to claim 3, characterized in that: 5. Said means for generating an attenuation control signal comprises level shifting means for generating said first attenuation control signal. 2. Device according to claim 1, characterized in that it is coupled to controllable damping means. 6. Code division multiple access communication device having a local oscillator signal and an intermediate frequency (IF) signal An apparatus for controlling transmission power of: means for generating an attenuation control signal; a first controllable coupled to the local oscillation signal to generate an attenuated local oscillation signal; a first controllable attenuation means that changes the attenuation in response to the attenuation control signal; damping means; a second controllable signal coupled to the 1F signal to produce a first attenuated IF signal; a second controllable damping means for varying the damping in response to the damping control signal; damping means coupled to said second controllable damping means and said first damped I a third controllable attenuation means for generating a second attenuated IF signal from the F signal; third controllable attenuation means for varying attenuation in response to the attenuation control signal; said first controllable damping means and said third controllable damping means; generating a transmission frequency signal from the attenuated local oscillation signal and the second attenuated IF signal; mixing means comprising: the transmitting frequency signal having a first power level; filtering means coupled to said mixing means for producing a filtered transmit frequency signal; and amplifying the filtered transmit frequency signal and generating a second power level greater than the first power level; amplification means for generating a signal for transmission having a power level; A device characterized by comprising: 7. Said means for generating an attenuation control signal comprises level shifting means for generating said first attenuation control signal. 7. Device according to claim 6, characterized in that it is coupled to controllable damping means. 8. The level shifting means controls the attenuation of the first controllable attenuation means. 8. The apparatus of claim 7, wherein the attenuation control signal is delayed. 9. Code division multiple access communication device having a local oscillator signal and an intermediate frequency (IF) signal An apparatus for controlling transmission power of: means for generating an attenuation control signal; level shifting means for generating a level shifted and delayed attenuation control signal; a first controllable coupled to the local oscillation signal to generate an attenuated local oscillation signal; attenuation means responsive to said level-shifted and delayed attenuation control signal; a first controllable damping means for varying the damping; a second controllable signal coupled to the IF signal and generating a first attenuated IF signal; a second controllable damping means for varying the damping in response to the damping control signal; damping means coupled to said second controllable damping means and said first damped I a third controllable attenuation means for generating a second attenuated IF signal from the F signal; third controllable attenuation means for varying attenuation in response to the attenuation control signal; said first controllable damping means and said third controllable damping means; generating a transmission frequency signal from the attenuated local oscillation signal and the second attenuated IF signal; mixing means comprising: the transmitting frequency signal having a first power level; filtering means coupled to said mixing means for producing a filtered transmit frequency signal; and amplifying the filtered transmit frequency signal and generating a second power level greater than the first power level; amplification means for generating a signal for transmission having a power level; A device characterized by comprising: 10. A code division multiple access communication device capable of transmitting and receiving signals: Oscillating means for generating a local oscillation signal; a modulating means for generating an intermediate frequency (IF) signal; and a means for controlling transmission power. Yes: means for generating an attenuation control signal; a first controllable coupled to the local oscillation signal to generate an attenuated local oscillation signal; a first controllable attenuator for changing the attenuation in response to the attenuation control signal; damping means capable of a second controllable attenuator coupled to the 1F signal to produce an attenuated IF signal; a second controllable attenuation for varying the attenuation in response to the attenuation control signal; means coupled to said first controllable damping means and said second controllable damping means. A transmission frequency signal is obtained from the attenuated local oscillation signal and the attenuated IF signal. a mixing means for producing; means for controlling transmission power; A code division multiple access communication device comprising: